Magnetic shift register coupling loop



Dec. 17, 1963 WAY DONG WOO MAGNETIC SHIFT REGISTERCOUPLING LOOP Filed Dec.

m/aam I WA) DONG W00 ATTORNEY 3,li i,87 Patented Dec. 17, 1963 3,114,397 MAGNETIC SHEFT REGESTER CGUPLH\IG TAX Way Dong Woo, Newton Qenter, Mass, assignor to Minneapolis-Honeyweil Regulator Company, Minneapolis, Minn, a corporation of Delaware Filed Dec. 16, 1957, er. No. 702,849 9 Claims. (Cl. 34ii174) A general object of the present invention is to provide a new and improved magnetic core shift register circuit. More specifically, the present invention is concerned with an improved magnetic core type shift register which is characterized by its simplicity, its adaptability to use components of relatively wide tolerance, and its ability to function at relatively high repetition rates.

Magnetic core shift registers are widely used for the storing, transferring and manipulation of digital data which may be represented by various time spaced electrical impulses. Certain types of magnetic cores have been found to be particularly adapted for use with electrical impulses for the reason that, if the core has bistable characteristics, it may be used to store information which is of the binary or on-off type. The type of core particularly useful in this type of circuit is one having a substantially square hysteresis characteristic and a substantial residual flux characteristic. The two residual flux points of the hysteresis characteristic define the two stable states of the core.

The switching of the flux condition in the core from one residual state to the other, produces a large flux change which will induce a large output signal in a winding which may be placed upon the core. The polarity of this output signal will be dependent upon the direction of the switching of the flux in the core. In a shift register, the signals shifted from the core are generally transferred out through an output winding and coupled into the input winding of a subsequent core which may be set by the signals supplied thereto. Thus, with a series of such cores connected in a chain, the signals may he stepped along through the cores to a utilization circuit.

In accordance with the principles of tr e present invention, there has been provided a new and improved magnetic core shift register with a new type of coupling link between the cores in the register. Here, the coupling link comprises an electronic switching device which is adapted to be switched to a conducting state by the switching of the flux condition within the magnetic core. When the switch is in the conducting state, it controls the current flow through an inductor element. When the switch is cut off, the current flow which has been established in the inductor element is directed into the next core in the register to set the core.

It is accordingly a further more specific object of the present invention to provide a new and improved magnetic core register incorporating a coupling link which comprises an electronic switch which will control the current flow through an inductor element and where the current flow induced in the inductor element may be directed into a further circuit for setting a further magnetic core.

An electronic switch particularly adapted for use in this combination is a transistor in that the current levels and voltage levels associated with the magnetic core circuits are quite compatible with the transistor operational characteristics. In one form of the invention, the transistor functions in a regenerative manner to control current flow in an inductor element in accordance with the fiuX signal produced in a core to which the transistor is coupled. The inductor element then is effectively coupled in a further circuit to a control winding or input winding of a subsequent core and this subsequent core will be set by this current flow.

It is a further more specific object of the present invention to provide a new and improved magnetic core shift register incorporating a transistor as an electronic switching device for controlling the current flow in an inductor element, the latter functioning to provide a control signal for a core positioned in the register.

As will be apparent from a detailed study of the present invention, the use of a single storage element between the cores of the core register considerably enhances the time response characteristic of the circuit without adversely atfectnig the wave forms of the signals required for the setting and switching in the cores in the register. The single storage element may well take the form of an air core inductor which functions as a temporary storage element as the signal is switched out of one core and read into a subsequent core.

It is, therefore, a still further more specific object of the invention to provide a new and improved coupling link for a magnetic core circuit which comprises a single inductor element whose current flow may be utilized for the storing temporarily of a signal being coupled between two magnetic cores.

The foregoing objects and features of novelty which characterize the invention as well as other objects of the invention are pointed out with particularity in the claims annexed to and forming a part of the present specification. For a better understanding of the invention, its advantages and specific objects attained with its use, reference should be had to the accompanying drawing and descriptive matter in which there is illustrated and described a pre ferred embodiment of the invention.

Referring to the single figure, four representative stages of a magnetic core shift register are illustrated which incorporate the principles of the present invention. The principal element of the register is the magnetic core, four of which are shown and are identified by the numerals 10, Ed, 39, and it). Each of the cores has an input winding which is so connected with respect to the magnetic core that when an input signal is applied thereto, the core may be assumed to be switched to the one stable state. The input windings for the cores are identified by the numerals M, 21, 31 and 41.

In order to initiate the switching of a core from the one stable state to the zero stable state, there is provided a trigger winding on each of the cores. These trigger windings are connected to a suitable trigger source which supplies a signal to the core so phased as to initiate a flux reversal in the core from the state to which it may have been switched by the input windings. The trigger windings on the cores are identified by the numerals 12, 22, 32, and 42.

Each of the cores of the circuit has a pair of output windings. These output windings are connected in a regenerative sense with a switching device which takes the form of a transistor. Thus, on core 10, there are provided a pair of output windings l3 and 14 with the winding 13 connected to the base electrode of a transistor 15 and the winding 14 being connected to the emitter of a transistor 15.

The output windings for the cores Zil, 3d and 40 are 23 and 24, 33 and 34, and 43 and 44, respectively. The electronic switch for the core 2% is the transistor 25 while the electronic switch for the core 30 is transistor 35.

Connected in series with each of the emitter circuits is a current limiting resistor. These current limiting resistors are identified by the reference numerals 16, 26 and 36.

The transistors of each coupling link are arranged to control the flow of current through an inductor and this current flow will be derived from a B- lead which is common ot all of the inductors of the register. The inductors for the stages illustrated are identified by the numeral-s 17, 27 and 37.

The individual inductors are each coupled to an input Winding by way of a closed series circuit which includes a resistor and a diode, the latter functioning to block any current flow during the interval when the associated transistor is initiating current flow in the inductor. The diode and resistor associated with the inductor 17 is the diode 18 and resistor !19. Associated with the inductor 27 is the diode 28 and resistor 29. Associated with the inductor 37 is the diode 38 and the resistor 39.

In considering the operation of the apparatus, it should first be noted that the number of turns on the output windings 13, .23, 33 and 43 is greater than the number of turns on the output windings r14, 24, 34 and 44. This will mean that the magnitude of the voltage induced in the winding 16 will be greater than that induced in the winding 14. Similarly, the voltage induced in the winding 23 will be greater than that of the winding 24' and the voltage in the winding 33 will be greater than that of the winding 3'4.

It is first assumed that each of the cores 10, 20, 3'0 and 40 are in their reset or zero stable state. When in this state, the application of a trigger pulse to the windings 12, 22, 32, and 42, will have substantially no effect in producing any appreciable flux change within the cores and consequently the apparatus will remain in the reset state. *In other words, the phasing of the trigger pulse is such that when it is applied to the trigger windings on the respective cores with the invention illustrated, the trigger pulse normally tends to switch the core from its 'one state to its zero state. Since the core is already in the zero state, the circuit will remain substantially unchanged.

When an input signal is applied to the input winding 11, the polarity of this signal will be such as to cause the core to switch from its zero state to a one state. Once the core has been switched to this one state, the applica- 'tion of a trigger pulse to the winding 12 will initiate a resetting of the core back to its zero state and the transfer of the signal stored therein into the next core 20.

More specifically, if a trigger pulse is applied to the winding 12 it tends to create a flux change in the core- '10 in such a direction as to induce in the winding 113 a potential which is negative on the terminal to which the base of the transistor '15 is connected. This voltage will be sufficiently more negative than the voltage induced in the winding 14, which will also have a negative potential thereon at the emitter terminal, to cause the transistor to become conductive. The current flow circuit through the transistor may be traced from the ground terminal through the resistor \16, winding 14, the emitter-collector circuit of transistor '15, inductor 17 to the B terminal.

The current flowing in the winding 114 is in a direction to aid the resetting of the core 10 and the resultant regenerative action by way of the windings I14 and 13 creates a rapid switching of the core from its one state back to the zero state. A relatively large current flow through the inductor 17 results. As soon as the core has switched, the current flow through the transistor 15 ceases and the emitter-collector path of the transistor 1'5 becomes a high impedance. The current flow through the inductor 17, which must dissipate through some path, is directed through the winding '21, resistor 19 and diode 18 in a closed series circuit. Since the current is flowing through the winding 21, where is enters at the undotted side, it is effective to set the core into the one state.

Upon the application of the next trigger pulse to the trigger windings of the cores, the core 20' acting upon the pulse received through its trigger winding 22, is switched in the manner described above with respect to the core 10. The signal thus generated by the core 20, will then be propagated through the coupling network into the core 30. It will be apparent that this switching and transfer of the signal will continue on through to the core 40 and thence to a utilization circuit as each trigger pulse is applied to the trigger windings of all the cores.

From the foregoing description, it wili be apparent that the major storage element between the cores of the register is the inductor. This inductor may well be an air core inductor and. one which. may be selected, together with the other components of the circuit, to have a relatively short time constant. As a result of the rapid operation of the circuit, the repetition rate, or the rate at which a signal is transferred through the register, may be considerably increased over that which was possible with the coupling circuits heretofore utilized. It will further be apparent that the number of components required in order to achieve this coupling between the cores is minimized from circuits heretofore known without any accompanying loss of circuit flexibility and usefulness.

While, in accordance with the provisions of the statutes, there has been illustrated and described the best form of the invention known, it will be apparent to those skilled in the art that changes may be made in the apparatus described without departing from the spirit of the invention as set forth in the appended claims and that in some cases, certain features of the invention may be used to advantage without a corresponding use of other features.

What is claimed as new and novel and for which it is desired to secure Letters Patent is:

1. Electrical apparatus comprising a plurality of bistable magnetic cores, each of said cores having an input winding, an output winding, and a trigger winding, means connecting said trigger windings in series to a trigger source, means connecting the output winding of one core to an input winding of a succeeding core comprising a controllable electronic switch and an inductor connected to said switch, said inductor being adapted to have 2. current flow induced therein when there is an output signal on said output winding, and means coupling the current flow in said inductor to said input winding, said last named means comprising a diode connected in series with said input winding, said diode being poled to block from said input winding the current flowing through said switch.

2. Electrical apparatus comprising a plurality of bistable magnetic cores, each of said cores having an input winding, an output winding, and a trigger winding, and means connecting the output winding of one core to an input winding of a succeeding core comprising a transistor nad an inductor connected in a first series circuit to said output winding to induce a current flow in said inductor when there is an output signal on said output winding, and means coupling the current flow in said inductor to said input winding, said last named means comprising a diode connected in a second series circuit with said input winding and poled to pass current from said inductor only when said transistor is cut off.

3. Electrical apparatus comprising a plurality of bistable magnetic cores, each of said cores having an input winding, a pair of output windings, and a trigger winding, and circuit means connecting the output winding of one core to an input winding of a succeeding core, said circuit means comprising a transistor regeneratively coupled to said pair of output windings and an inductor connected in series with one of said output windings to induce a current flow in said inductor when there is an output signal on said output winding, and means coupling the current fiow in said inductor to said input winding, said last named means comprising a diode connected in a series circuit with said input winding and poled to block current flowing through said transistor.

4. A coupling link for a magnetic core shift register including bistable magnetic cores each having an input winding and an output winding, comprising a controllable electronic current controlling device, winding means including said output winding for regeneratively connecting said current controlling device to its associated core, an inductor connected in series with said current controlling device, a diode, and means including said diode connecting said inductor in series with the input winding of the succeeding core, said diode being connected to direct the current flow in said inductor to said last-recited input winding when said current controlling device is cut oif.

5. A coupling link for a magnetic core shift register including bistable magnetic cores each having an input winding and an output winding, comprising a controllable electronic current controlling device, winding means including said output winding for regeneratively connecting said current controlling device to its associated core, an inductor connected in a first series circuit with said current controlling device and a source of power, a diode, and means including said diode connecting said inductor in series with the input winding of the succeeding core, said diode being connected to direct the current flow in said inductor to said last-recited input winding when said current controlling device is cut off.

6. A shift register comprising a pair of bistable magnetic cores, each of said cores having an input winding, an output winding, and a trigger winding, a power source, a transistor associated with each of said cores having an emitter-collector circuit connected in series between said output winding of said associated core and said power source, an inductor connected in series with said last named series circuit, and a diode connecting said inductor in series with the input winding of the next succeeding core, said diode being poled to block the current flowing through said transistor.

7. A shift register comprising -a pair of bistable magnetic cores, each of said cores having an input winding, a pair of output windings, and a trigger Winding, a power source, a transistor associated with each of said cores having an emitter-collector circuit connected in series between one of said output windings of said associated core and said power source, means regeneratively connecting the other of said output windings of said core to the base of said transistor, an inductor connected in series with said one output winding, and an asymmetrically conducting device connecting said inductor in series with the input winding of the next succeeding core, said last named device being poled to block the current flowing through said transistor.

8. A shift register comprising a pair of bistable magnetic cores, each of said cores having an input winding,

an output winding, and a trigger winding, a power source, a transistor associated with each of said cores having an emitter-collector circuit connected in series between said output winding of said associated core and said power source, an inductor connected in series with said last named series circuit, and a series connected resistor and diode connecting said inductor in a closed series circuit with the input winding of the next succeeding core, sajid diode being poled to block the flow of current through said transistor.

9. A shift register comprising a plurality of bistable magnetic cores, each of said cores having an input winding, a trigger winding, and first and second output windings, said second output winding having a greater number of turns than said first output Winding, circuit means coupling the first :output winding of one core to an input winding of a succeeding core, said circuit means comprising a transistor having its emitter coupled to said first output winding and its base coupled to said second output winding, an inductor connected between the collector of said tnansistor land a source of negative DC. potential, said inductor being adapted to have current flow induced therein upon the occurrence of an output signal in said first and second output windings, and means for coupling the current flow in said inductor to said input Winding of said succeeding core, said last-recited means comprising a diode connected in a series circuit with said input winding and poled to block current flowing through said transistor.

References Cited in the file of this patent UNITED STATES PATENTS 2,652,501 Wilson Sept. 15, 1953 2,747,110 Jones May 22, 1956 2,763,780 Skelton et a1. Sept. 18, 1956 2,849,624 Snyder Aug. 26, 1958 2,876,438 Jones Mar. 3, 1959 2,902,609 Ostroff et al. Sept. 1, 1959 2,907,006 Echert Sept. 29, 1959 2,955,264 Kihn et al Oct. 4, 1960 2,963,688 Arnerniya Dec. 6, 1960 2,970,294 Guterman Jan. 31, 196 1 

1. ELECTRICAL APPARATUS COMPRISING A PLURALITY OF BISTABLE MAGNETIC CORES, EACH OF SAID CORES HAVING AN INPUT WINDING, AN OUTPUT WINDING, AND A TRIGGER WINDING, MEANS CONNECTING SAID TRIGGER WINDINGS IN SERIES TO A TRIGGER SOURCE, MEANS CONNECTING THE OUTPUT WINDING OF ONE CORE TO AN INPUT WINDING OF A SUCCEEDING CORE COMPRISING A CONTROLLABLE ELECTRONIC SWITCH AND AN INDUCTOR CONNECTED TO SAID SWITCH, SAID INDUCTOR BEING ADAPTED TO HAVE A CUR- 